Don't ask for a name in the landing page, redir to the room/meeting

Instead of asking the user for a name in the landing page, it just
redirects to the room/meeting page, where the user is asked to enter a
name. If the user is signed in, no redirect is necessary and the user's
name is used automatically.

app/helpers/application_helper.rb

@@ -43,6 +43,11 @@ module ApplicationHelper
     end
   end
 
+  # Whether the current page is the page of a room/meeting or not
+  def on_room_or_meeting_page?
+    params[:id].present?
+  end
+
   def version
     Greenlight::VERSION
   rescue